Methods of making pyrrolidones

ABSTRACT

The present invention provides methods for making N-methylpyrrolidine and analogous compounds via hydrogenation. Novel catalysts for this process, and novel conditions/yields are also described. Other process improvements may include extraction and hydrolysis steps. Some preferred reactions take place in the aqueous phase. Starting materials for making N-methylpyrrolidine may include succinic acid, N-methylsuccinimide, and their analogs.

RELATED PATENT DATA

This patent resulted from a divisional application of U.S. patentapplication Ser. No. 09/884,602, which was filed on Jun. 18, 2001.

STATEMENT OF GOVERNMENT RIGHTS

This invention was made with Government support under contractDE-AC0676RLO 1830 awarded by the U.S. Department of Energy. TheGovernment has certain rights in this invention.

FIELD OF THE INVENTION

The present invention relates to methods of making pyrrolidones,especially N-methyl pyrrolidone (“NMP”), by hydrogenation.

BACKGROUND OF THE INVENTION

Olsen, in U.S. Pat. No. 4,841,069 described reactions of succinicanhydride, methanol and hydrogen. In Example 1, Olsen described areaction in which 67 g of succinic anhydride, 62 g of methanol, and12.53 g of ammonia were heated 5 hrs in an autoclave at 300° C. withstirring. Olsen reported that 100% of the succinic anhydride wasconverted with a selectivity to N-methylsuccinimide (“NMS”) of 90%. InExample 11, Olsen described a reaction in which 65 g of succinicanhydride, 41 g of methanol, and 12.15 g of ammonia, 12 g of 5%palladium on carbon catalyst, and 700 psig of hydrogen were heated 21hrs at 290° C. with stirring. Olsen reported that 100% of the succinicanhydride was converted with a 60% selectivity to N-methylsuccinimideand a 30% selectivity to N-methylpyrrolidone.

Olsen, in U.S. Pat. No. 4,814,464 (which is very similar to U.S. Pat.No. 4,841,069), described the same or similar ammonolysis-alkylationreactions in which a succinic derivative such as the anhydride, acid ordiester is reacted with ammonia and a C₁ to C₄ alkanol and converted toan N-alkylsuccinimide. Olsen stated that “In general, the reactants,substrate, ammonia, and alkanol, are used in about stiochiometricproportions. Too little ammonia or alkanol results in incompleteconversion, and too much ammonia is wasteful and produces undesirableby-products.” However, Olsen also states that “preferably excess of thealcohol is used.” It is reported that products can be separated bydistillation or crystallization. See Col. 3, lines 50-59.

Olsen also remarked that the N-alkylsuccinimide can be reducedcatalytically with hydrogen either continuously or batchwise. In Example1, Olsen reported hydrogenating NMS at 230 C. for 2 hours over a nickelcatalyst to yield a 60% NMS conversion with an 89% selectivity to NMP.In Example 3, Olsen reported reacting 73 g dimethylsuccinate, 37 gammonium hydroxide, 12 g of 5% palladium on carbon catalyst, and 700psig of hydrogen for 21 hrs at 290 C. with stirring. Olsen reported that100% of the dimethylsuccinate was converted with a 70% selectivity toN-methylsuccinimide and a 20% selectivity to N-methylpyrrolidone.

Koehler et al., in U.S. Pat. No. 5,101,045, described a process for thepreparation of N-substituted pyrrolidones by catalytic hydrogenation ofmaleic anhydride, maleic acid and/or fumaric acid in the presence ofammonia, a primary alcohol and a modified cobalt oxide catalyst. InExample 3, Koehler et al. stated that 75 ml of a 45% aqueous diammoniummaleate solution and 75 ml methanol were hydrogenated for 42 hours at230 C. in the presence of 10 g of a modified cobalt oxide catalyst.Koehler et al. reported that the product contained 89 mol % NMP, 5.0 mol% pyrrolidine and methylpyrrolidine, and 2.7 mol % of succinimide andmethylsuccinimide.

Liao, in U.S. Pat. No. 3,092,638, and Hollstein et al., in U.S. Pat. No.3,681,387, described hydrogenating succinimide. Hollstein et al. run thehydrogenation in water over a palladium on carbon catalyst.

Liao, in U.S. Pat. No. 3,080,377, Himmele et al., in U.S. Pat. No.3,198,808, Hollstein et al., in U.S. Pat. No. 3,681,387, and Pesa et al.in U.S. Pat. No. 4,263,175 described hydrogenating succinic acid orsuccinic anhydride in the presence of ammonia to yield 2-pyrrolidone.Catalysts used include: palladium on carbon, ruthenium on carbon,ruthenium on alumina, and cobalt oxide. Himmele et al. stated that anammonium salt can be used in place of ammonia.

Chichery et al., in U.S. Pat. No. 3,448,118, and Weyer et al. in U.S.Pat. Nos. 5,157,127 and 5,434,273, disclosed methods of makingN-substituted pyrrolidones in which succinic anhydride, succinic acid,or the like is hydrogenated in the presence of a primary amine. Chicheryet al. run their hydrogenations in water with a palladium on charcoalcatalyst. Weyer et al. used a modified cobalt oxide catalyst.

zur Hausen et al., in U.S. Pat. No. 4,780,547, described hydrogenationof NMS over a nickel catalyst. In Example 2, zur Hausen et al. statedthat comparable results can be obtained using succinic anhydride andmethylamine in place of NMS.

SUMMARY OF THE INVENTION

The invention provides methods of making a compound having the formula:

wherein R₁, R₂, R₄, and R₅ are, independently, H or a C₁ to C₆ alkyl orsubstituted alkyl; and R₃ is H or a C₁ to C₆ alkyl or substituted alkyl.These methods involve hydrogenation.

In a first aspect, a composition containing a compound having theformula:

wherein R₁, R₂, R₄, and R₅ are, independently, H or a C₁ to C₆ alkyl orsubstituted alkyl; or wherein R₂ and R₄ together are replaced by adouble bond; R₃ is H or a C₁ to C₆ alkyl or substituted alkyl; and X andY are, independently, OH, O⁻, or where X and Y together are a bridgingoxo; is reacted with hydrogen, in the presence of water and a catalyst.Preferably, the catalyst includes carbon, metal oxide and at least onemetal selected from Pd, Rh, Pt, Ru, Ni or Co. In some embodiments, acompound of formula (A) is purified prior to hydrogenation. Thus, insome embodiments, a compound of formula (C) is made in a process havingat least 3 steps. In a first step, a compound of formula (B) is reactedwith an ammonia source, in the presence of water, to form a compoundhaving formula (A). Then, in a second step, the compound of formula (A)is extracted into an organic solvent. In a third step, the compound offormula (A), that was extracted in the second step, is hydrogenated inthe presence of a catalyst.

It has also been surprisingly discovered that, in some processes, theyields of compound (C) can be increased substantially by hydrolyzingcompositions formed during hydrogenation reactions of compounds (A)and/or (B). A portion of the composition formed by hydrogenating (A)and/or (B) can be hydrolyzed (i.e., reacted with water) to produce acompound or compounds of formula (C); this portion is referred to as acompound (C) precursor. To prevent over-reduction (and lower yields),the compound (C) precursor is separated from hydrogen, the hydrogenationcatalyst, or both hydrogen and the catalyst.

In another aspect, the invention provides a method of making a compoundof formula (C), in which a composition including a compound having theformula:

wherein R₁, R₂, R₄, and R₅ are, independently, H or a C₁ to C₆ alkyl orsubstituted alkyl; and R₃ is H or a C₁ to C₆ alkyl or substituted alkyl;is reacted with and hydrogen in the presence of a Pd, Rh, Pt, Ru, Ni orCo catalyst; at a temperature of less than 220° C. and for a time ofless than 10 hours. In this method, compound (C) is obtained in a yieldof at least 80%.

Advantages of various embodiments of the present invention include:higher yields, better purity, more stable catalysts, lower reactiontemperatures, shorter reaction times, and lower costs. Unexpectedlysuperior results were discovered under various conditions, including:using a metal oxide (such as zirconia) textured catalyst; hydrogenatinga succinimide below 220° C. for less than ten hours; and hydrogenatingaqueous phase compositions having a relatively high concentration ofcompound (B).

For fermentation or other biologically-derived compositions, it isdesirable to separate out proteins and other contaminants, prior to thehydrogenation to produce compound (C). For example, proteins in thesecompositions could poison a hydrogenation catalyst. Thus, there may beimportant advantages in separating out an imide, such as compound A, andhydrogenating the extracted imide. An extraction step prior to theformation of N-methylpyrrolidine can produce unexpectedly superiorresults, especially for biologically-derived starting materials.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a one-step reaction of diammonium succinate to2-pyrrolidone and NMP.

FIG. 2 illustrates a two-step reaction of diammonium succinate orsuccinimide to NMP.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Reactants in the inventive process include the compounds (A) and (B)described above. Preferably, R₁, R₂, R₄, and R₅ are H or a lower alkyl,preferably methyl, ethyl or propyl, more preferably R₁, R₂, R₄, and R₅are all H. X and Y can be the same or different and preferably are OH orO⁻(such as in an ionic oxygen species such as O⁻[NH₄]⁺. In somepreferred embodiments, X and Y together are a single bridging oxygen ananhydride such as succinic anhydride. Typically, X and Y are in anequilbrium such as between OH and anhydride or between O⁻[NH₄]⁺ andOH+NH₃. R₃ is preferably H or a lower alkyl, preferably methyl, ethyl orpropyl; most preferably, R₃ is methyl.

The reactants may come from a variety of sources. For example, succinicacid can be produced in situ from hydrogenation of maleic acid. In somepreferred embodiments, the reactant composition is derived fromfermentation or other biological process and will typically be in anaqueous solution or mixture (also referred to as an aqueous compositionor aqueous phase composition).

When it is desirable to convert a compound of formula B (which for thepurposes of this disclosure can be called a “succinate”), the reactionmixture must contain an ammonia source, most typically ammonia orammonium. The ammonia source can be added, such as by adding gaseous oraqueous ammonia, or can be present in the succinate feedstock, such asaqueous diammonium succinate. Preferably, ammonia (including ammonium)is present in a range of 1 to 3 molar ratio of ammonia to succinate,more preferably 1 to 2. Ammonia can be present in the feedstock or addedbefore or during the reaction. The succinate is preferably in aqueoussolution, preferably having a concentration of 5 to 60 weight %, morepreferably 15 to 30 wt. %. The reaction mixture preferably contains analcohol, R₃OH where R₃ is a C₁ to C₆ alkyl or substituted alkyl,preferably methanol. The alcohol may be formed in situ, but ispreferably added to the reaction mixture as an alcohol. It has beenfound that the reaction is sensitive to alcohol content, with higheralcohol content leading to higher yields of the N-alkylated product suchas NMP. Preferably, the alcohol is present in a ratio (alcohol:compoundB) of at least about 2:1. The reaction preferably occurs in water.

The reactant (A) can be hydrogenated in solution or neat. In preferredembodiments, the reactant (A) is obtained from compound (B) and purifiedbefore hydrogenation. In many cases, the purified compound (A) mayconvert to product in greater yield and with fewer side products than anunpurified mixture. Most preferably, (A) is N-methyl-succinimide (NMS).

The product pyrrolidone, compound (C), preferably has the same R₁-R₅ asin the reactant compound or compounds. In some preferred embodiments,the product is N-methyl pyrrolidone (NMP).

Formation of product (C) from compounds (A) or (B) requireshydrogenation over a hydrogenation catalyst. Preferably the catalystcontains Rh, Pd, Pt, Ru, Ni or Co which are active metals for thishydrogenation. More preferably, catalyst also contains Re, such as inPd—Re or Rh—Re. The hydrogenation catalyst typically includes a poroussupport material. Supports selected in the present invention arepreferably selected to be stable in the reactor environment in whichthey are intended for use. Preferably, the supports arehydrothermally-stable, meaning that the support loses less than 15% ofits surface area after 72 hours in water at 150° C. More preferably, thesupport is hydrothermally-stable such that it loses less than 5% of itssurface area after 72 hours in water at 150° C. Preferred supportmaterials include porous carbon and rutile. An especially preferredsupport is a porous, high surface area activated carbon, such as carbonswith CTC values around 120%, available from Calgon and Engelhard. Forgood dispersion of the catalytic sites, the support preferably has ahigh surface area and a pore volume of 10 to 98%, more preferably 30 to90%.

In preferred embodiments, a metal oxide is disposed on the poroussupport. Preferably, for aqueous phase applications, the oxide containsat least one of Zr, Ti, Hf, Ta, Nb, Mo, and W. Preferably, the metaloxide contains at least 50%, more preferably at least 90%, by mass of anoxide or oxides of one or more of Zr, Ti, Hf, Ta, Nb, Mo, and W. In someembodiments, the metal oxide is substantially completely composed of anoxide or oxides of one or more of Zr, Ti, Hf, Mo, and W. The rutile formof titania is especially preferred. In alternative embodiments, oxidesof other elements such as Si, Al, Zn, Sn, V, Fe, U, Th, etc. may beused. The metal oxide is preferably present in 1 to 25 weight %, morepreferably 5 to 10 weight percent of the total weight of the driedcatalyst. Typically, the metal of the metal oxide is fully oxidized (forexample TiO₂, ZrO₂, etc.) with terminal or bridging oxides; however, inless preferred embodiments the oxide could contain, in addition tooxygen, hydrogen in hydroxyls (which may be difficult to differentiatefrom hydrated oxides), sufides, cations, oxygen-containing anions, andthe like. The catalyst metal (such as Pd, Rh, etc. includingcombinations of catalyst metals) is preferably present in 0.1 to 10weight %, more preferably 2.5 to 5.0 weight percent of the total weightof the dried catalyst.

In some preferred embodiments, the catalyst is characterized by one ormore of the following characteristics: a minimum, smallest dimension ofat least about 100 μm, more preferably at least about 300 μm; at least70%, more preferably at least 80% of the catalyst component is withinabout 5 μm, more preferably about 2 μm, of 80% of the minimum area ofthe metal oxide. Preferably, at least about 5%, more preferably at leastabout 10%, of the catalyst component, and at least about 5%, morepreferably at least about 10%, of the metal oxide is disposed in poresthat are at least about 10 μm, more preferably at least about 20 μm,away from the exterior of the support. The foregoing properties areconducted by cutting a catalyst particle or monolith to obtain across-section of at least about 100 μm in both height and width. Themetal oxide is then imaged by an elemental analysis spectroscopictechnique, and the minimum area that encompasses 80% of the metal oxideis then identified. This area (or areas) is then increased by a 5 (or 2)μm margin around each area or areas. Then, the distribution of catalystin the cross-sectional area is imaged by an elemental analysisspectroscopic technique; at least 70% of the catalyst component iswithin the area of the 80% of metal oxide (including the margin).Amounts of each element is quantified by intensity. It is not necessarythat all cross-sections exhibit the characteristics described herein,but, for a desired catalyst, at least some cross-section has thesecharacteristics. Preferably, the 80% of the metal oxide plus 5 μm marginoccupies less than 90%, more preferably less than 40%, of the totalcross-sectional area. The converse preferably also occurs, that is, atleast 70%, more preferably at least 80%, of the metal oxide is withinthe minimum area of 80% of the catalyst component plus a 5 (or 2) μmmargin around each area or areas.

Preferably, at least about 50% of the catalyst component is within about10 μm of the exterior of the support. In some embodiments, some internalpores have at least 2 times, and in some cases at least 3 times, as muchof the catalyst component as compared with the metal oxide. In preferredembodiments, the majority, more preferably at least about 80%, ofcatalyst component, and/or the metal oxide, that is located within theinterior of the support (that is, that portion of the catalyst componentand/or metal oxide which is at least about 10 μm from the exterior ofthe support) is located in pores having at least one dimension of atleast about 5 μm. The foregoing values are measured based on SEManalysis of cross-sections of catalysts.

Some preferred embodiments of the inventive catalysts may,alternatively, be described with reference to the method by which thecatalyst is made. Alternatively, some preferred embodiments of theinvention can be described by reactivities. For example, in somepreferred embodiments, the catalyst exhibits a succinic acid conversionof at least 50% after 5 hours under the conditions set forth in Table 1.

Catalysts are preferably made by solution/colloid techniques. A poroussupport may be purchased or prepared by known methods. A metal oxide solis prepared or obtained. A sol may be prepared, for example, bydissolving a metal compound and adding water or changing pH to form asol. Each of the oligomeric or colloidal particles in the sol contain ametal and oxygen; these particles may also contain other components suchas halides, cations, etc. The sol could be prepared, for example, bydissolving a metal alkoxide, halide, etc. in an anhydrous solvent, thenadding sufficient water to form a sol. In some preferred embodiments,organic solvents are avoided and the sol is prepared only in water.Conditions for preparing sols will depend on the type of metal andavailable ligands. In some preferred embodiments, the sol is prepared atbetween about 10 and about 50° C. In some preferred embodiments, inaqueous solutions, the sol is preferably formed at a pH of between 1 and6, more preferably between 2 and 5. The metal oxide precursor sol iscontacted with the porous support. This could be done, for example, bydipping the support in the sol or colloid, or dispersing the sol in avolume of solvent equivalent to the incipient wetness of the support, sothat the solvent exactly fills the void fraction of the catalyst uponcontacting and is dried to deposit the metal oxide on the surface of thesupport. In the case of a particulate support, such as activated carbonpowders, the support and metal oxide precursor composition can be mixedin a suspension. The porous support is preferably not coated by avapor-deposited layer, more preferably the method of making the catalystdoes not have any vapor deposition step. The catalyst component can bedeposited subsequent to, or simultaneous with, the deposition of themetal oxide. The catalyst component can be impregnated into the supportin a single-step, or by multi-step impregnation processes. In apreferred method, the precursor for the catalyst component is preparedin a sol that is deposited after, or codeposited with, the metal oxideprecursor sol. In some preferred embodiments, the precursor for thecatalyst component is prepared under the same conditions as the metaloxide precursor sol, for example as an aqueous colloidal mixture in thedesired pH range. After the metal oxide and catalyst component have beendeposited, the catalyst is typically dried. Also, following deposition,if desired, the catalyst component can be activated by an appropriatetechnique such as reduction under a hydrogen-containing atmosphere.

The inventive reactions can be accomplished in a one-step (A or B to C)or a two-step reaction (B to C). In some preferred embodiments, B isconverted to A in a continuous process, and the resulting compound A ishydrogenated in a batch or continuous process. Preferably, A is purifiedprior to hydrogenation.

One example of a one-step reaction is illustrated in FIG. 1. Asuccinate, such as 20 weight % aqueous diammonium succinate, ishydrogenated in aqueous methanol at 265° C. and 1900 psi H₂ to produce2-pyrrolidone (hereinafter referred to as “2-py,” which is also known as2-pyrrolidinone) and N-methylpyrrolidone. This route is conducted as aone step process; however, it has been found that the reaction proceedsthough an N-methylsuccinimide intermediate. 2-py and NMP are obtained ina 90% yield based on the diammonium succinate starting material. Theratio NMP:2-py is about 2:1.

An example of a two-step reaction is illustrated in FIG. 2. In the firststep of this route, a succinate, such as 20 weight % aqueous diammoniumsuccinate or succinimide, is reacted with methanol at about 300° C. toproduce N-methylsuccinimide. The first step does not require a catalyst.In the second step, aqueous N-methylsuccinimide is hydrogenated at 200°C. and 1900 psi H₂ for about 8 hours to produce NMP. The hydrogenationis conducted over a catalyst of Rh/ZrO₂/C or Rh—Re/C. Followinghydrogenation, NMP can be isolated by distillation. If residues arepresent, the non-distilled residue is subjected to hydrolysis.

In some preferred embodiments, the succinimide produced in the firststep is extracted into an organic solvent. Extraction solvents mayinclude alkanes (such as hexane), toluene, etc., and preferredextraction solvents include ethers and halocarbons. It has been foundthat chloroform is an excellent extraction solvent. Extractions can beconducted batchwise or in a continuous process.

For the one step reaction, temperature is preferably in the range of 200to 350° C., more preferably 230 to 280° C. For the two-step reaction,better results are obtained if the second step is conducted at a lowertemperature than the first step. The first step, which may be conductedin the absence of a catalyst, is preferably conducted at 250 to 350° C.,more preferably 280 to 320° C. The second step, which requires ahydrogenation catalyst, has been found to yield better results ifconducted at relatively low temperature, preferably at less than 230°C., more preferably at 180 to 220° C., and still more preferably 190 to210° C.

Another important variable is time. As is well-known, shorter reactiontimes are more economical and thus highly desirable. Preferably,reaction time for the one step process is less than about 24 hours, morepreferably about 4 to about 10 hours. In the two-step process, reactiontime for the first step is less than about 4 hours, more preferably lessthan about 0.5 hours. In some embodiments, time for the first step isabout 0.2 to about 2.5 hours, preferably less than 1 hour. Reaction timefor the second step is preferably less than about 24 hours, morepreferably less than one hour, and in some embodiments about 10 minutesto about 10 hours, more preferably 10 to 30 minutes. In some preferredembodiments, the hydrogenation can be described as a function of timeand mass of catalyst; preferably at least one half gram of reactant(preferably NMS) hour per gram catalyst, i.e., at least (0.5 g reactantconverted)(h)/(g catalyst). Alternatively, the hydrogenation preferablyoccurs at a rate of at least (20 g reactant converted)(h)/(g catalystmetal).

Hydrogenation is preferably conducted at a pressure of 600-1800 psi,more preferably 1000-1400 psi.

The reactions can occur in any reactor suitable for use under thedesired conditions of temperature, pressure, and solvent. Examples ofsuitable apparatus include: trickle bed, bubble column reactors, andcontinuous stirred tank.

It has been discovered that methods of the present invention can producesurprisingly high yields at selected conditions and reaction times. Inpreferred embodiments of the one step reaction, product C (preferablyNMP) is obtained in a yield of at least 70%, more preferably at least80%, in some preferred embodiments, NMP and 2-py are obtained in greaterthan 90% yield and an NMP/2-py ratio of at least 2.0. Yield of NMS ispreferably at least 70% to about 90%, more preferably at least 80%.Conversion of NMS to NMP in methods of the present invention arepreferably at least 70% to about 90%, more preferably at least 80%, withNMP/2-py ratio of at least 5, more preferably at least 50. Yields aremeasured by gas chromatography. The product can be purified by knownprocedures such as distillation or extraction.

In some preferred embodiments, at least a portion of the productcomposition obtained from a hydrogenation reaction is hydrolyzed andeither recovered or recycled back into a reactor. The yield ofpyrrolidones diminishes at long reaction times in the presence ofhydrogen and a hydrogenation catalyst—this may be due to over-reductionof products. Therefore, the hydrolysis process is preferably conductedby removing the presence of either the hydrogen or the catalyst or both.

Hydrogenation of compounds (A) and/or (B) may result in a productcomposition containing compound (C) and a compound (C) precursorcomposition, where hydrolysis of the precursor composition yieldsadditional compound (C). Following removal of hydrogen and/orhydrogenation catalyst, any portion of the product composition could behydrolyzed. For example, the product composition could be hydrolyzed asa continuous stream. The hydrolysis reaction could also be accomplished,for example, by a packing the second half of a continuous flow reactorwith an inert heat transfer packing so that following the conversion ofan aqueous feedstock to a liquid product composition, the liquidcomposition could remain at hydrolysis reaction conditions outside ofthe presence of catalyst. Additionally, a secondary inert packed reactorcould follow the primary reactor and gas/liquid separator to remove thehydrogen, and the secondary reactor could be operated at any desirabletemperature and pressure combination that would result in the highestyield of product. Alternatively, compound (C) could be recovered, forexample by distillation, from the product composition and theundistilled composition hydrolyzed to produce additional compound (C).Since higher yields of compound (C) precursor composition may resultfrom lower temperature hydrogenation, in some embodiments, hydrogenationis conducted at below 200° C., in some embodiments the hydrogenation isconducted in the range of 150-200° C. The composition to be hydrolyzedpreferably contains at least 20% by weight water, more preferably atleast 50 wt. % water. Hydrolysis preferably is conducted at above 200°C., in some embodiments, in the range of 200-300° C. In someembodiments, hydrolysis is conducted for 2 to 15 hours.

EXAMPLES

Catalyst Preparation Examples

All catalysts prepared in the following examples were prepared on 20×50mesh Engelhard 712A-5-1589-1 coconut shell carbon granules (nominal CTCnumber ˜95%). Liquid holding capacity of the Engelhard carbon wasdetermined to be ˜0.76 cc/g (determined using the method of incipientwetness using D.I. water). A commercially prepared Rh(NO₃)₃ solution(10.37% Rh by wt.) was used as the source of Rh for the Rh-containingcatalyst.

5% Rh/C Catalyst 16.0071 g of the carbon granules were weighed into a 2oz wide mouth glass jar, then the jar containing the carbon was cappedand set aside until needed. The liquid holding capacity of the 16.0071 gof carbon was calculated as 12.2 cc. The required wt. of Rh needed wascalculated as follows:

[(16.0071 g C÷0.95)−16.0071 g]=0.84 g Rh required

The amount of the above Rh(NO₃)₃ solution was calculated as follows:

0.84 g Rh needed÷0.1037=8.12 g of the Rh(NO₃)₃ solution.

8.13 g of the Rh(NO₃)₃ solution (10.37% Rh by wt.) was weighed into anempty 25 ml graduated cylinder. Additional DI water was added so thatthe total solution volume was 12.2 ml (total solution wt.=13.9635 g).The contents of the graduated cylinder were then well mixed to insurehomogeneity. The 12.2 cc of the above prepared Rh(NO₃)₃ solution wasadded dropwise (in ˜0.8ml increments) to the 16.0071 g of carbongranules that had been previously weighed out. The jar was recappedfollowing each ˜0.8 ml addition of solution and shaken vigorously toinsure uniform wetting of the carbon. After all of the solution had beenadded to the jar containing the carbon, the jar was allowed to stand foran additional ˜30 minutes to allow the solution to completely soak intothe pores of the carbon. After standing for the ˜30 minute period, thecontents were again shaken vigorously to insure uniformity. The cap wasthen removed and placed in a vacuum oven to dry overnight (oventemperature=100° C.; under house vacuum).

2.5% Rh/2.5% Zr/C Catalyst 15.99 g of the carbon granules were weighedinto a 2 oz wide mouth glass jar, then the jar containing the carbon wascapped and set aside until needed.

ZrO(NO₃)₂.xH₂O (anhydrous FW=231.23 g/mole) was used as the source of Zrfor this catalyst. 3.37 g of DI water and 0.41 g of 70% HNO₃ solutionwere added to a 25 ml graduated cylinder. Next, 1.0741 g ofZrO(NO₃)₂.xH₂O was added to the graduate and the mixture heated on ahotplate until all of the ZrO(NO₃)₂.xH2O was dissolved. 4.09 g of theRh(NO₃)₃ solution (10.37% Rh by wt.) was added to the graduate alongwith enough DI water to bring the total solution volume up to 12.2 cc.The contents of the graduated cylinder were then well mixed to insurehomogeneity. The 12.2 cc of the above prepared Rh and Zr containingsolution was added dropwise (in ˜0.8ml increments) to the carbongranules that had been previously weighed out. The jar was recappedfollowing each ˜0.8 ml addition of solution and shaken vigorously toinsure uniform wetting of the carbon. After all of the solution had beenadded to the jar containing the carbon, the jar was allowed to stand foran additional ˜30 minutes to allow the solution to completely soak intothe pores of the carbon. After standing for the ˜30 minute period, thecontents were again shaken vigorously to insure uniformity. The cap wasthen removed and placed in a vacuum oven to dry overnight (oventemperature=100° C.; under house vacuum).

2.5% Rh/2.5% Re/C Catalyst 16.00 g of the carbon granules were weighedinto a 2 oz wide mouth glass jar. A commercially available perrhenicacid solution (54.5% Re by wt.) was used as the source of the Re forthis catalyst. 0.778 g of perrhenic acid solution (54.5% Re by wt.) and4.0666 g of Rh(NO₃)₃ solution (10.37% Rh by wt.) were weighed into a 25ml graduated cylinder and enough DI water added to bring the totalsolution volume up to 12.2 cc. The 12.2 cc of Rh and Re containingsolution was first well mixed to insure homogeneity, then addeddropwise, in ˜0.8 ml increments, to the jar containing the 16.00 g ofcarbon. The jar was recapped and shaken vigorously after each liquidaddition. After all of the liquid had been added, the jar was allowed tostand capped for an additional 30 minutes to allow the liquid to soakinto the pores of the carbon. After standing, the jar and its contentswere again shaken vigorously to thoroughly mix the contents. The cap wasthen removed, and the open jar and its contents placed in a vacuum ovento dry overnight (oven temperature=100° C.; under house vacuum). Thedried catalyst was loaded into the reaction chamber and reduced in situ.

Semi-Batch Reactor Run Examples

Table 1 contains a summary of semi-batch reactor run results showing howthe choice of catalyst, feedstock, and process conditions can affectreaction rates and product selectivities in the liquid phase synthesisof pyrrolidinones. The first 11 entries in the table are representativeof hydrogenation reactions involving aqueous phase feedstocks. Theentries in Table are representative of hydrogenation reactions offeedstock materials performed in non-aqueous solvents. The descriptionof the preparation of the feedstock solutions, the catalyst pretreatmentprocess, and the semi-batch reactor run procedures are described below.Table 2 contains a summary of semi-batch reactor results showing how thechoice of feedstock and process conditions can affect the reaction ratesand product yields in the non-catalytic, hydrothermal synthesis ofN-methylsuccinimide.

Preparation of Aqueous Feedstock Solutions Used in Semi-Batch RunExamples

Aqueous Feedstock Solution #1

244.18 g (2.068 moles) of succinic acid was weighed into a ½ gallon polybottle. Next, 583.76 g (32.400 moles) of DI water was also added to thebottle. The contents of the bottle were then gently agitated to try tobreak up lumps of solid succinic acid, and to try to wet all of thesolid. Next, 239.17 g (4.142 moles NH₃ & 9.360 moles H₂O) ofconcentrated ammonia solution (29.5% NH₃ by wt.) was added to theslurried mixture in the bottle. The bottle, containing the succinicacid/ammonia mixture, was then recapped to prevent the loss of material.The capped bottle was again agitated to enhance the mixing of thereactants. The bottle warmed to ˜50° C. due to the neutralizationreaction, and was cooled down to room temperature by holding the bottleunder cold, running water for several minutes. All of the solid succinicacid, initially present, had dissolved and remained in solution afteragain reaching room temperature. Next, 133.07 g of methanol were addedto the solution in the bottle, the bottle re-capped, and then shakenvigorously to thoroughly mix the resulting solution. The composition ofthe resulting solution was as follows:

Succinic Acid = 20.35% (by wt.) NH₃ = 5.88% (by wt.) Methanol = 11.09%(by wt.) H₂O = 62.69% (by wt.)

The approximate molar ratio of this feedstock solution is approximatelyas follows:

NH₃/Succinic Acid/Methanol/H₂O=2.0/1.0/2.0/20.2

This feedstock solution was used in examples 1, 2, 3, & 5 in Table 1 andalso in examples 1 & 2 in Table 2.

Aqueous Feedstock Solution #2

101.74 g (0.862 mole) of succinic acid was weighed into a 500 ml polybottle along with 271.22 g (15.055 moles) of DI water. The mixture wasgently agitated to break up the lumps of solid succinic acid, and to tryto wet all of the solid. Next, 99.48 g of concentrated ammonia solution(29.5% NH₃ by wt.) (1.723 moles NH₃+3.893 moles H₂O) was added to themixture in the bottle, the bottle re-capped, then shaken vigorously.After shaking, the bottle and its contents were cooled to roomtemperature. 27.60 g (0.861 mole) of methanol were added to the solutionin the bottle, the bottle re-capped, then shaken to thoroughly mix thecontents. The composition of the resulting solution was as follows:

Succinic Acid = 20.35% (by wt.) NH₃ = 5.87% (by wt.) Methanol = 5.52%(by wt.) H₂O = 68.27% (by wt.)

The approximate molar ratio of this feedstock solution was approximatelyas follows:

NH₃/Succinic Acid/Methanol/H₂O=2.0/1.0/1.0/22.0

This feedstock solution was used in example 4 in Table 1.

Aqueous Feedstock Solution #3

101.74 g (0.8615 mole) of succinic acid and 320.92 g (17.8138 moles) ofDI water were weighed into a 500 ml poly bottle. The mixture was gentlyagitated to break up the lumps of solid succinic acid, and to try to wetall of the solid. Next, 49.74 g of concentrated ammonia solution (29.5%NH₃ by wt.) (0.861 moles NH₃+1.9465 moles H₂O) was added to the mixturein the bottle, the bottle re-capped, then shaken. After shaking, thebottle and its contents were cooled to room temperature. 27.60 g (0.861mole) of methanol were then added to the solution in the bottle, thebottle re-capped, then shaken to thoroughly mix the contents. Thecomposition of the resulting solution was as follows:

Succinic Acid = 20.35% (by wt.) NH₃ = 2.93% (by wt.) Methanol = 5.52%(by wt.) H₂O = 71.20% (by wt.)

The approximate molar ratio of this feedstock solution was approximatelyas follows:

NH₃/Succinic Acid/Methanol/H₂O=1.0/1.0/1.0/23.0

This feedstock solution was used in examples 6 & 7 in Table 1.

Aqueous Feedstock Solution #4

68.22 g (0.6031 mole) of N-methylsuccinimide (NMS) and 281.78 g (15.64moles) of DI water were weighed into a 500 ml poly bottle. The bottlewas re-capped then shaken vigorously for several minutes until all ofthe NMS appeared to have dissolved. The composition of the resultingsolution was as follows:

N-methysuccinimide = 19.49% (by wt.) H₂O = −80.51% (by wt.)

The approximate molar ratio of this feedstock solution is approximatelyas follows:

N-methylsuccinimide/H₂O=1.0/25.9

This feedstock solution was used in examples 8, 9, 10 & 11 in Table 1.

Aqueous Feedstock Solution #5

85.37 g (0.8615 mole) of succinimide and 387.06 g (21.4852 moles) of DIwater were weighed into a 500 ml poly bottle. Next, 27.60 g (0.8614mole) of methanol was added to the mixture in the bottle, the bottlere-capped, then shaken vigorously. After shaking the bottle and itscontents for ˜15 minutes all but a small amount of the solid materialappeared to have gone into solution (the amount of remaining undissolvedsolid material was probably less than ˜0.2 g). The composition of theresulting solution was as follows:

Succinimide = 17.07% (by wt.) Methanol = 5.52 % (by wt.) H₂O = 77.41%(by wt.)

The approximate molar ratio of this feedstock solution was approximatelyas follows:

Succinimide/Methanol/H₂O=1.0/1.0/24.9

This feedstock solution was used in example 3 in Table 2.

Aqueous Feedstock Solution #6

85.37 g (0.8615 mole) of succinimide, 359.42 g (19.9509 moles) of DIwater, and 55.21 g (1.7232 mole) of methanol were weighed into a 500 mlpoly bottle. The bottle was then capped and the contents shakenvigorously for ˜10 minutes. Undissolved material remained after thatamount of time, so the capped bottle was held under hot running waterfor ˜10 minutes (with occasional shaking). Even after holding under hotwater for that amount of time, there still appeared to be ˜0.1 g ofundissolved white solid in the container. Upon cooling to roomtemperature, no additional white solid material appeared to fall out ofsolution. The composition of the resulting solution was as follows:

Succinimide = 17.07% (by wt.) Methanol = 11.04% (by wt.) H₂O = 71.88%(by wt.)

The approximate molar ratio of this feedstock solution was approximatelyas follows:

Succinimide/Methanol/H₂O=1.0/2.0/23.2

This feedstock solution was used in examples 4 & 5 in Table 2.

Aqueous Feedstock Solution #7

106.71 g (1.0769 mole) of succinimide and 324.33 g (18.0031 moles) of DIwater were weighed into a 500 ml poly bottle. The bottle was then cappedand the contents shaken to dissolve the solid. It was necessary to heatup the contents of the bottle slightly by holding the bottle under hotrunning water. After heating the solution to ˜37° C. almost all of thesolid had dissolved. The cap was removed and 69.09 g (2.156 moles) ofmethanol was added to the mixture. The bottle was again re-capped andshaken to mix the contents, then allowed to cool to room temperature. Asmall amount of white solid fell out of solution upon cooling.Re-warming the solution (to ˜40° C.) was found to be sufficient tore-dissolve the solids. The composition of the resulting solution was asfollows:

Succinimide = 21.34% (by wt.) Methanol = 13.85% (by wt.) H₂O = 64.85%(by wt.)

The approximate molar ratio of this feedstock solution is approximatelyas follows:

Succinimide/Methanol/H₂O=1.0/2.0/16.7

This feedstock solution was used in example 6 in Table 2.

Description of the Semi-Batch Reactor System

Examples 1-11 of Table 1 and examples 1-6 of Table 2 were conducted in amodified 450 ml Parr autoclave system constructed of Hastelloy®C. Thesystem incorporated a sealed magnetically driven stirrer assembly,internal cooling loop, internal control thermocouple, 0-3000 psigpressure gauge, and filter-ended dip tube. The dip tube was used bothfor gas and liquid addition to the reactor vessel (but notsimultaneously) and also for the removal of liquid product samples takenperiodically during the runs. The reactor system was set up to run undera relatively fixed hydrogen or nitrogen pressure during the runs. Thiswas accomplished by setting the gas cylinder delivery pressure to thedesired run pressure (in advance of the run), then opening the vessel tothe gas delivery system once the desired run temperature had beenreached. The dip tube fitting had separate shutoff valves for the gasaddition and liquid addition/removal. The shut off valve to the gasdelivery system was closed prior to drawing out a liquid product sample.After sampling, the liquid shut off valve would be re-closed and the gasfeed shutoff valve re-opened to the gas delivery system. A small changein the observed system pressure was usually encountered for the durationof the sampling period. The reactor vessel was electrically heated (Parrreactor heating jacket) and used a Parr temperature controller equippedwith an integral tachometer and variable speed control. Times requiredfor the initial heat up to run temperature were generally ˜½ hour induration.

Catalyst Pre-Treatment Procedures Used in Semi-Batch Reactor RunExamples (Pyrrolidinone Synthesis Runs)

Prior to use, all of the catalyst preparations described herein, wereactivated by an appropriate chemical reduction procedure. For all of theexamples given in this document the catalyst activation procedure isaccomplished via hydrogen reduction at an appropriate temperaturecondition. For all of the semi-batch run examples, the catalystpretreatments (hydrogen reductions) were conducted in the semi-batchreactor vessel (450 cc Parr autoclave), prior to the addition of theliquid feedstock solution. All of the catalysts used in examples 1-11 inTable 1 were Rh-based catalysts prepared on the same carbon supportmaterial, and therefore all of the catalyst preps used in those examplesreceived identical catalyst pre-treatments (H₂ reductions). In allcases, the weight of the dried, un-reduced catalyst preparation wasnominally 3.75 g which was placed into a clean, dry reactor body. Therest of the reactor was then assembled and connected to the gas feedsystem, the cooling water lines, the rupture disc line, the controlthermocouple connector, and to the stirrer drive motor. Followingpressure testing, the reactor vessel was purged with N₂ or Argon toinsure that all of the residual air was removed from the vessel prior tothe addition of hydrogen. After purging with either N₂ or Argon, thevessel is pressurized to 400 psig with whichever of the two inert gaseswere initially used. Next, 100 psig of additional hydrogen pressure isadded to the reactor vessel and the vessel subsequently sealed off(reduction mixture was effectively a 20% H₂ in N₂ or Ar mixture). Theinternal stirrer is started and set at ˜150 rpm to provide some internalmixing of the gasses inside the reactor vessel. Once the stirrerstarted, the reactor vessel was heated to 120° C., where the temperaturewas maintained for a period of 4 hours. At the end of the 4 hours, thetemperature controller was turned off, and the reactor vessel allowed tocool to room temperature. The spent reduction gasses were then ventedfrom the reactor and the reactor again purged with N₂ or Argon.

Aqueous Feedstock Solution Addition and Procedure Used to ConductSemi-Batch Reactor Run Examples (Pyrrolidinone Synthesis Runs)

The aqueous feedstock solution was added to the reactor vessel throughthe liquid addition/removal port on the reactor. Typically, ˜150 cc ofliquid feedstock solution was added to the reactor. After the liquidfeedstock solution was added, the system was initially purged withhydrogen gas to remove air that may have gotten into the reactor vesselduring the liquid addition. The vessel was pressurized to ˜500 psig withH₂, and the gas inlet line to the reactor vessel closed. The internalstirrer was turned on and adjusted to ˜500 rpm, then the system washeated up to the desired run temperature. When the reactor vesselreaches the desired run temperature, a sample of the liquidfeedstock/product solution was removed from the reactor vessel, then thevessel was opened to the gas delivery system and the reactor pressurerose to the pre-set desired run pressure. The time when the reactorsystem was opened up to the gas delivery system is designated T=0 hrs.,or the time that the run is considered to have been started. Periodicliquid product samples were withdrawn from the reactor vessel andanalyzed to monitor the disappearance of starting materials and theformation of reaction products. Product samples are numbered accordingto how many hours had expired between the run start time and the timethat a particular sample had been removed from the reactor. Forinstance, if the run start time for a particular reaction were 9:00 A.M.and a sample was withdrawn from the reactor at 10:30 A.M. (˜1.5 hoursafter the run start time), then the sample would be designated as theT+1.5 hr. sample. The product samples were analyzed by gaschromatography and conversion and product selectivity data calculatedfor each catalyst and set of reaction conditions.

Description of NMS Synthesis Runs Conducted in the Semi-Batch ReactorSystem

Examples 1-6 of Table 2 were all examples of the non-catalyzed,hydrothermal synthesis of NMS from either diammonium succinate/methanolor succinimide/methanol mixtures. The reactions were conducted atelevated temperatures using a nitrogen cover gas. In these runs, thefeedstock solution (˜150 ml) was generally added to the reactor vesselfollowing the usual pressure testing procedure. After the liquid hadbeen added to the reactor vessel, the vessel was purged with nitrogen,to remove any air that may have gotten into the vessel during the liquidfeedstock addition. Next, the reactor vessel was pressurized withadditional nitrogen gas (typically 600-1000 psig depending upon thefinal run temperature) then closed off to the pressurized gas deliverysystem. The internal stirrer was turned on and adjusted to ˜500 rpm,then the system was heated up to the desired run temperature (either265° C. or 300° C.). A sample of the feed/product solution would betaken when the setpoint temperature was reached, then the reactor vesselwould be opened up to the pressurized gas delivery system (pre-set toeither 1900 or 2200 psig of N₂ pressure). Periodic liquid productsamples were withdrawn from the reactor vessel and analyzed to monitorthe disappearance of starting materials and the formation of reactionproducts. The product samples were analyzed by gas chromatography andconversion and product selectivity data calculated for each catalyst andset of reaction conditions. Table 1 contains a summary of semi-batchreactor run results showing how the choice of catalyst, feedstock, andprocess conditions can affect reaction rates and product selectivitiesin the liquid phase synthesis of pyrrolidinones.

TABLE 1 Synthesis of NMP - Semibatch Process Results Temp. PressureFeedstck % Conv. Max. Yield of NMP/2py catalyst (° C.) (MPa) solutionTime, (hr) at max. yield NMP + 2-py (%) mole ratio 5% Rh/C 265 13 1 21.098.5 83.3 1.58 2.5% Rh/2.5% Zr/C 265 13 1 21.3 97.5 95.2 2.31 2.5%Rh/2.5% Re/C 265 13 1 8.0 90.6 90.0 1.15 5% Rh/C 265 13 2 5.0 95.5 80.70.55 2.5% Rh/2.5% Re/C 200 13 1 24.0 93.5 47.2 0.21 5% Rh/C 265 13 3 7.089.6 70.9 0.86 2.5% Rh/2.5% Zr/C 200 13 3 23.5 80.4 24.8 0.16 5% Rh/C265 13 4 8.0 95.6 74.1 2.15 2.5% Rh/2.5% Re/C 265 13 4 5.0 88.7 53.75.28 2.5% Rh/2.5% Zr/C 200 13 4 24.0 93.5 81.1 38.1 2.5% Rh/2.5% Re/C200 13 4 8.0 94.8 88.8 67.3 All tests at 1900 psig (13.2 MPa)

As can be seen from the results in Table 1, increasing methanolincreased the ratio of NMP. In a one-step reaction, better results maybe obtained in a range of about 230 to 280° C. Higher N-alkyl (e.g. NMP)yields are obtained at an alcohol:compound B ratio of at least 2.Surprisingly, we discovered that a metal oxide-containing catalystresulted in superior results (see, for example, Example 2). Also,unexpectedly, by hydrogenating a succinimide in the presence of a Pd orRh catalyst, at a temperature less than about 220 ° C. for less than 10hours, we found that compounds (C), preferably NMP, can be obtained in ayield of at least 80%.

TABLE 2 Synthesis of NMS Temp. Pressure Feedstock Time, (hr) Max. Yield% con- (° C.) (MPa) Solution at max. yield of NMS (%) version 265 13 13.0 66.9 100 300 13 1 3.5 83.3 100 265 13 5 4.0 43.2 75.3 300 13 6 2.582.3 97.8 300 15 6 3.0 79.0 99.1 300 13 7 0.5 87.5 89.0

As can be seen from Table 2, among other results, we discovered thatsurprisingly superior results are obtained from aqueous phasehydrogenations in which the molar ratio of compound (B):water is atleast about 0.06, in some preferred embodiments in a range of 0.06to0.2.

Continuous Flow Reactor Run Examples

Preparation of Aqueous Feedstock Solutions Used in Continuous FlowReactor Run Examples

Aqueous Continuous Feedstock Solution #1

114.73 g (1.014 moles) of N-methylsuccinimide (Aldrich Chemical Co.) wasweighed into a 1000 ml Erlenmeyer flask along with 474.01 g (26.312moles) of deionized water. The contents of the flask were vigorouslystirred until all of the soluble material had gone into solution. Asmall quantity (estimated to be less than 0.02 g) of black coloredinsoluble material remained suspended in the otherwise colorlesssolution. The black particles were removed by filtering. The compositionof the resulting solution was as follows:

N-methylsuccinimide = 19.49% (by wt.) H₂O = −80.51% (by wt.)

The approximate molar ratio of this feedstock solution is approximatelyas follows:

 N-methylsuccinimide/H₂O=1.0/25.9

Aqueous Continuous Feedstock Solution #2

200.00 g (1.768 moles) of N-methylsuccinimide (Aldrich Chemical Co.) wasweighed into a 32 oz Nalgene® poly bottle along with 826.18 g (45.861moles) of DI water. The bottle was capped and shaken vigorously untilall of the solid material had dissolved. The composition of theresulting solution was as follows:

N-methylsuccinimide = 19.49% (by wt.) H₂O = −80.51% (by wt.)

The approximate molar ratio of this feedstock solution is approximatelyas follows:

N-methylsuccinimide/H₂O=1.0/25.9

Description of the Continuous Flow Reactor System

Examples 1-7 of Table 3 were generated in a small continuous flowreactor system configured as a trickle bed reactor. In this reactorconfiguration both gas and liquid feeds are introduced into the reactorin a co-current downflow manner. The reactor tube itself is an AutoclaveEngineers 316 SS medium pressure reactor tube (0.750″ O.D. ×0.098″ wallthickness with coned and threaded ends). An internal thermowell tube({fraction (3/16)}″ O.D. heavy walled 316 SS tube welded shut on oneend) runs from the bottom end up through the entire heated length of thereactor tube, so that the reactor's temperature profile can be probed.The reactor tube is jacketed by a 2″ diameter ×18″ long heat exchangerthrough which hot oil is circulated to provide uniform heating of thereactor tube (catalyst is generally packed within the middle 14″ of the18″ heated zone; bed temperatures can generally be maintained within+/−˜0.5° C.). The oil was heated and circulated by a Julabo closedsystem heated pump. Liquid feeds were supplied to the reactor by an ISCOhigh-pressure syringe pump, equipped with a syringe heating jacket andheated liquid delivery lines. The liquid delivery line and gas deliveryline entered the reactor together via an Autoclave Engineers “tee” atthe top end of the reactor tube. Feed gases were metered into thereactor using Brooks high-pressure mass flow controllers. The gas feedsto the mass flow controllers were provided by a manifolded gas deliverysystem at constant pressure. A dome-loaded back-pressure regulator wasused to maintain the reactor at the desired system pressure. Gaseous andliquid products are separated in chilled collection vessels, whereliquid products were periodically drawn off and analyzed. Gaseousmaterials were measured with a wet test meter, and gas samples wereperiodically withdrawn and analyzed by gas chromatography.

The catalyst used in the continuous flow reactor was made by anincipient wetness catalyst preparation technique. This was done bytaking a 18.34 g sample of an Engelhard carbon (CTC=95%, incipientwetness of 0.76 cc/g) to prepare a 2.5% rhodium and 2.5% rheniumcatalyst. The impregnation volume of this preparation was 13.9 ml. Theamounts of rhodium and rhenium are specified as final weight percent ofthe reduced metal on the carbon support. Thus, the required weight ofactive metal precursor was back calculated to determine the necessaryweight of rhodium nitrate and perrhenic acid. For this example, 0.48 gof rhodium metal was required, and thus 4.65 of rhodium nitrate stocksolution was required (at 10.51% rhodium metal by weight). Also, 0.48 gof rhenium metal was required, and thus 0.93 g of perrhenic acid wasrequired (at 52.09% rhenium metal by weight). 0.93 g of perrhenic acidand 4.67 g of rhodium nitrate was added to a graduated cylinder andstirred. The solution was then topped up to a final volume of 14 ml,stirred, and allowed to stand for 5 minutes. The solution was then addedin 1 to 2 ml aliquots to the jar containing the 18.34 g of carbon. Aftereach addition, the jar was capped and shaken until the carbon flowedfreely in the vessel. Upon addition of the entire volume of solution,the carbon was sticky and slightly clumped. The carbon sat closed atroom temperature with intermittent agitation for 3 hours and appeareddry and mostly granular, with some material still adhering to the wallsof the jar. The support was then placed uncapped in a vacuum oven set to100° C. and 20 in Hg house vacuum and left to dry overnight. Thecatalyst was reduced prior to use.

The reactor body was packed with about 10 ml of crushed quartz followedby 0.5 cm of quartz wool. The 2.5%Rh/2.5%Re on Engelhard 95%CTC carboncatalyst was added in 10 ml increments, followed by light tamping toachieve uniform packing. Upon addition of 40 ml (18.31 g) of catalyst,the bed was capped with another 0.5 cm of quartz wool. The reactor wasthen assembled in the flow reactor test stand. The catalyst was firstreduced at 120 C. for 16 hours under a cover gas of 4% hydrogen in argonat atmospheric pressure. Upon reduction, the cover gas was switched tohydrogen flowing at 18 SLPH and the pressure raised to 13 MPa while thecolumn temperature was changed to the first operating point of 200° C.After equilibrating the temperature and gas flow rate, the liquid feedwas added via high pressure Isco liquid pump at 100 ml/hr. From previoustrickle bed experience, a total of 3 or more bed volumes of feed wereallowed to pass through the reactor before it was consideredequilibrated. Upon equilibration, approximately 20 to 30 ml of productwas collected in a sample vial before the reactor conditions wereadjusted and allowed to equilibrate again. During each sample period, agas sample was taken from the low pressure side of the back pressureregulator and subjected to fixed gas analysis. The samples wereimmediately transferred to a refrigerator and batched for analysis on aGC. Prior to idling the reactor following a series of run conditions,approximately 3 bed volumes of deionized water was passed across thereactor, and the reactor was lowered to 100° C. and held at pressureunder reducing conditions with a low flow of hydrogen until the nextfeed and series of run conditions. Results are shown in Table 3.

TABLE 3 Synthesis of NMP - Continuous Flow Reactor Feedstock 1 1 1 2 2 22 H₂ flow (slph) 18.2 18.2 14.4 8.3 8.3 18.2 18.2 H₂/NMS 4.3 4.3 4.6 4.24.2 4.6 4.6 psi 1900 1900 1900 1900 1900 1900 1200 Temp. (° C.) 200 180180 200 220 250 250 feed (ml/hr) 100 100 80 50 50 100 100 conversion %93.6 78.0 85.3 98.7 99.4 97.8 88.2 NMP selec. 55.5 50.0 52.4 57.1 60.064.1 75.7 2-py selec. 0.7 0.0 0.0 1.1 1.8 0.0 0.6

Hydrolysis Examples

A composite testing feedstock was prepared by combining productsobtained from the continuous flow testing (columns 2 and 3 of Table 3).The analysis of this composite is shown in the Table 4. 56.18 g of thismaterial was loaded into a 300 ml Parr autoclave, sealed, and the purgedrepeatedly with nitrogen. The autoclave was stirred at 500 rpm, and acover gas of nitrogen was used to pressurize the autoclave to 4 MPa. Thereactor heater was turned on to a set point of 250° C. After 30 minutes,the reactor achieved 250 ° C. and the pressure of nitrogen was increasedto 9 MPa. The reactor was held at 250° C. and 9 MPa for 15.5 hours,after which it was quickly cooled and the sample removed for analysis.The results are shown in the table below:

TABLE 4 Hydrolysis initial final % Succinimide 0.05 0.00 %N-Methylsuccinimide 3.09 2.98 % Methanol 0.15 0.13 % Gamma-Butyrolactone0.15 0.04 % N-Methyl-2-Pyrrolidinone 6.42 10.42 % N-Butyl-2-Pyrrolidone0.02 0.03 % 2-Pyrrolidinone 0.00 0.00

As can be seen from the Table, hydrolysis treatment substantiallyincreased yield of the desired product NMP.

A second hydrolysis experiment conducted for a shorter time (1.6 hr)with the product obtained from the run in column 5 of Table 3 collectedfrom the continuous hydrogenation testing under the conditions of thefirst experiment showed no change in the NMP yield. The difference inthe results between the first and second experimental runs was likelydue to differences in hydrogenation conditions, although experimentalerror is also a possibility. The feedstock for the second hydrolysisexperiment was obtained from a run at higher temperature and slower flowrate—conditions that may not produce a compound (C) precursor compound.

Closure

While preferred embodiments of the present invention have beendescribed, it will be apparent to those skilled in the art that manychanges and modifications may be made without departing from theinvention in its broader aspects. The appended claims are thereforeintended to cover all such chances and modifications as fall within thetrue spirit and scope of the invention.

What is claimed:
 1. A method of making a compound having the formula:

wherein R₁, R₂, R₄, and R₅ are, independently, H or a C₁ to C₆ alkyl orsubstituted alkyl; and R₃ is H or a C₁ to C₆ alkyl or substituted alkyl;comprising a first step of reacting a composition comprising: a compoundhaving the formula:

wherein R₁, R₂, R₄, and R₅ are, independently, H or a C₁ to C₆ alkyl orsubstituted alkyl; or wherein R₂ and R₄ together are replaced by adouble bond; R₃ is H or a C₁ to C₆ alkyl or substituted alkyl; and X andY are, independently, OH, O⁻, or where X and Y together are a bridgingoxo; and an ammonia source, in the presence of water, to form a compoundhaving the formula:

wherein R₁, R₂, R₄, and R₅ are, independently, H or a C₁ to C₆ alkyl orsubstituted alkyl; or wherein R₂ and R₄ together are replaced by adouble bond; R₃ is H or a C₁ to C₆ alkyl or substituted alkyl; a secondstep of extracting the compound of formula (A) into an organic solvent;and a third step comprising hydrogenating the compound of formula (A),that was extracted in the second step, in the presence of a catalyst. 2.The method of claim 1 wherein the compound of formula (B) is in amixture resulting from fermentation.
 3. The method of claim 1 whereinthe organic solvent is an ether or a halocarbon.
 4. The method of claim1 wherein the catalyst comprises carbon, metal oxide and at least onemetal selected from the group consisting of Pd, Rh, Pt, Ru, Ni and Co.